Skip Navigation Links  The Library of Congress >> Researchers
Main Reading Room (Humanities and Social Sciences Division)
  Home >> Information for Researchers

Information for Researchers - Using the Library of Congress

Online Catalog

The Library of Congress Online Catalog contains approximately 14 million records representing books, serials, computer files, manuscripts, cartographic materials, music, sound recordings, and visual materials. The Online Catalog also displays searching aids for users, such as cross-references and scope notes. The catalog records reside in a single integrated database; they are not separated according to type of material, language of material, date of cataloging, or processing/circulation status. The Online Catalog is available on the Internet at

As an integrated database, the Online Catalog includes 3.2 million catalog records from an earlier database. These catalog records, primarily for books and serials cataloged between 1898 and 1980, are being edited to comply with current cataloging standards and to reflect contemporary language and usage. The legend "[from old catalog]" indicates that the headings may deviate from current Library of Congress cataloging policy. For a complete search of books and serials cataloged prior to 1980, researchers onsite at the Library should also use the Main Card Catalog.

Many items from the Library's special collections are accessible to users but are not represented in either the Online Catalog or the Main Card Catalog. In addition, some individual items within collections (microforms, manuscripts, photographs, etc.) are not listed separately in the Online Catalog or the Main Card Catalog, but are represented by collection-level catalog records. In many such cases, the reading room holding the items or collections will have specialized catalogs or finding aids for identifying the materials.

The Online Catalog includes romanized records for Chinese, Japanese, and Korean language material cataloged since 1984, Hebrew and Yiddish cataloged since 1988, and Arabic and Persian cataloged since 1991. These catalog records appear in the Library of Congress Online Catalog with English-language subject headings. In the future, the Online Catalog can display catalog records in the scripts containing non-Roman characters (e.g. Unicode characters) in any of the JACKPHY languages (Japanese, Arabaic, Chinese, Korean, Persian, Hebrew, and Yiddish).

At the Microform and Electronic Resources Center (LJ-139, the former Computer Catalog Center) near the Main Reading Room, reference librarians provide assistance to researchers using the computer system. The Microform and Electronic Resources Center (LJ-139, the former Computer Catalog Center) has a variety of equipment for people with disabilities.

Top of Page Top of Page
  Home >> Information for Researchers
  The Library of Congress >> Researchers
  December 1, 2016
Legal | External Link Disclaimer

Contact Us:
Ask a Librarian